1. Field of the Invention
The present invention relates to a blocking device with varying sensitivity for a strap-winder.
2. Description of the Prior Art
The automatic strap-winders and their special application to car safety belts are now well known. Such devices allow normal movements by the user but automatically lock in cases of impact to prevent protraction of the strap, the locking being effective by means of a device sensitive to the acceleration of the strap, the vehicle on both.
The present invention concerns an improvement of the devices sensitive to the acceleration of the strap, and more particularly, of the devices admitting of an element of inertia set on a mobile support equipped with return mechanism laid out so it will block the couple transmitted to the element of inertia by the protraction of the strap and acting on the mobile support in order to keep it out of its normal position of equilibrium and thus block the winder's reel in the unfolding direction. A device of this type is described in particular in the U.S. Pat. No. 3,858,824. Such a device usually includes an inertia wheel joined to the movement of the reel's axle by means of a cog-wheel and held by a support that turns on the reel's axle. The return of the support is normally insured by a spring that prevents the mobile support from moving when the strap is displaced in the protracting direction. When the protraction of the strap above is not enough to allow a very quick fastening of the strap and at the same time maintain enough sensitivity within the framework of the legal standards set in various countries.